Abstract
The present communication is a continuation, and in some respects a completion, of several preliminary researches which have been published from time to time during the past three years. On the hypothesis that a molecule may be distorted by the near approach of its neighbours, it has been shown how the presence of molecular groups, which vary in complexity with change of temperature, may modify the temperature coefficient of the magnetic property of a substance. The large change of molecular constitution during the transition from the liquid to the crystalline state should therefore be accompanied by a sudden change of the magnetic property.